Sterilization system and method of operation

ABSTRACT

A sterilization system adapted for use with a selectively enclosed space includes a conduit having an inlet adapted to draw air in from the enclosed space and an outlet adapted to exhaust air into the enclosed space. An ionizer is maintained in the conduit and in close proximity to the outlet and a UV-C lamp is maintained in the conduit. A blower having a blower vent is adapted to exhaust ambient air into the enclosed space and an air quality sensor is maintained in the conduit and in close proximity to the inlet to measure at least two parameters and selectively controls the ionizer, the UV-C lamp, and the blower based on whether threshold levels of the at least two parameters are exceeded or not.

FIELD OF THE INVENTION

The present invention is generally directed to a lift cabin sterilization system. In particular, the present invention is directed to a sterilization system which may be incorporated into an existing air conditioning system, or which may be provided independently, to maintain high air quality in an enclosed space.

BACKGROUND OF THE INVENTION

In view of the COVID-19 outbreak, the awareness of the importance of air quality—indoors and out—is heightened. In small or confined spaces, it is well recognized that bioaerosols threaten an occupant's health. It is further recognized that there are ways of spreading pathogens in a built environment. This may occur by direct spray from an infected individual, direct/indirect contact of contaminated surfaces (fomite transmission) and/or airborne transmission. Confined spaces, such as lift cabins in particular, also referred to as elevators, go through all levels of a building and also form congestion zones for all tenants and occupants. Such cabins are compact, less ventilated, and pose a very high risk for all building occupants.

It is known that regular exposure to fine particulate matter (PM_(2.5) and PM₁₀) provokes inflammation of lung cell membranes, which over long periods of time, leads to higher risk of microbial infections, including COVID-19, as well as increased symptom severity. Additionally, particulate matter can act as a vehicle or transport mechanism for the virus, allowing pathogens, including COVID-19, to be airborne for longer periods of time before being inhaled.

Another pollutant source is ozone (O₃) which can cause a range of lung related issues such as wheezing, shortness of breath, coughing, sore throat, and increased risk of asthma. Any of these can significantly aggravate symptoms linked to viral infections such as COVID-19 as well as increased transmissivity of the microbial infection.

Accordingly, there is a need in the art for an efficient and safe air sterilization system to mitigate fomite and airborne transmission of infectious diseases in confined spaces. There is a need in the art to provide a system to reduce and maintain airborne particulate matter PM_(2.5) and PM₁₀ at safe levels to mitigate the impacts of these particulate matter on human health as well as aggravating airborne transmission of infectious diseases. There is also a need in the art to reduce and maintain the ozone level to a safe level in indoor areas and chambers, such as lift cabins.

SUMMARY OF THE INVENTION

One or more embodiments of the present invention provide a sterilization system and method of operation.

Yet other embodiments of the present invention provide a sterilization system adapted for use with a selectively enclosed space, comprising a conduit having an inlet adapted to draw air in from the enclosed space and an outlet adapted to exhaust air into the enclosed space, an ionizer maintained in the conduit and in close proximity to the outlet, the ionizer releases charged ions to the air flowing through said conduit to selectively deactivating pathogens and air pollutants in the enclosed space and the conduit, a UV-C lamp maintained in the conduit, the UV-C lamp selectively deactivating contaminants in air flowing through the conduit, a blower having a blower vent adapted to exhaust ambient air into the enclosed space, and an air quality sensor maintained in the conduit and in close proximity to the inlet, the air quality sensor measuring at least two parameters, wherein the air quality sensor selectively activates and deactivates the ionizer, the UV-C lamp, and controls the blower based on whether threshold levels of the at least two parameters are exceeded or not.

Further embodiments of the present invention provide a method for sterilizing a selectively enclosed space, comprising installing a sterilization system in an enclosed space having an air conditioner, wherein the enclosed space has a conduit inlet and a conduit outlet associated with the air conditioner, and a blower vent, the sterilization system further comprising an ionizer, a UV-C lamp, and an air quality sensor maintained in the conduit, and a blower positioned near the blower vent, setting initial operating states of the blower to a minimum operating condition, the ionizer to an off condition and the air quality sensor and the UV-lamp to an on condition as an initial operating state, determining by the air quality sensor whether an ozone value exceeds a predetermined ozone threshold and, whether at least one particulate matter (PM) value exceeds at least one predetermined PM threshold and, wherein if both the ozone and PM values do not exceed their respective thresholds, the operating states of the ionizer, the blower, and the UV-C lamp remain in said initial operating state, wherein if both ozone and at least one PM value exceed their respective thresholds, the operating states of the ionizer is turned on and the blower is turned from the minimum operating condition to a maximum operating condition and the UV-C lamp remains on for a predetermined period of time, wherein if the ozone value exceeds the predetermined ozone threshold and the PM value does not exceed the at least one predetermined PM threshold value, the blower is turned to the maximum operating condition, the ionizer remains off, the said UV-C lamp is turned off for a predetermined period of time, and wherein if the ozone value does not exceed the predetermined ozone threshold value and the at least one predetermined PM value exceeds the at least one predetermined PM threshold value, the ionizer is turned on, the blower remains at the minimum operating condition and the UV-C lamp remains on for a predetermined period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an interior schematic diagram of a lift cabin sterilization system according to the concepts of the present invention;

FIG. 2 is a schematic diagram of a sterilizer control system utilized with or by the sterilization system according to the concepts of the present invention; and

FIG. 3 is a flowchart of a sterilizer control operational method according to the concepts of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Referring now to the drawings, it can be generally seen that the present invention is directed to a system for maintaining a high air quality inside lift cabins or elevators, other transport cubicles, a room, cell, or other enclosed space by using a combination of purification and sensor technology. Generally, the system includes an air purifier located within the lift cabin's air conditioning (AC) supply airflow, a UV-C lamp and an indoor air quality (IAQ) sensor also placed in a return duct and a fresh air blower fan. In one embodiment, the air purifier is a bipolar ionization air purifier. Skilled artisans will appreciate that the present invention may be used with any type of indoor area or room.

The system is designed to maintain high air quality standards for indoor spaces. This is achieved by using the IAQ sensor to detect when designated particulate matter thresholds are met, and then subsequently activating the purifier components to return air quality levels to an acceptable range below the thresholds. Additionally, the system provides for the ability to address ozone levels inside the cabin by utilizing a fresh air fan that recirculates fresh air into the cabin, based on a timer mechanism. Skilled artisans will appreciate that other indoor air quality parameters may be detected and adjusted to corresponding acceptable standards. Unlike conventional air purification products, this invention does not affect the interior design of the space, as all air purifier components may be incorporated into an existing heating/ventilation air conditioning (HVAC) system. Conventionally, purifier components (such as ionizers and UV lamps) are installed inside lift cabins and are controlled by motion sensors; such set up has the potential risk of irradiating the occupants. It will further be appreciated that the present invention does not use any filters in contrast to current air purification systems. Filters are undesirable as they add to maintenance costs for replacement and disposal and are also prone to retaining pathogens.

Specifically referring now to FIGS. 1 and 2, it can be seen that a lift cabin sterilization system is designated generally by the numeral 10. The system includes a cabin 12 which provides a floor 14, interconnected sidewalls 16 extending from the floor, and a ceiling 18 which also interconnects the sidewalls. A lift control panel 20 may be provided on one of the sidewalls so as to control operational movements of the cabin. The cabin 12 may also provide a door 24 which opens and closes at the appropriate times. The door may open and close based on user input from the control panel or input received from some other control feature. A blower vent 26 may be provided in the ceiling 18, or in some embodiments in the sidewalls 16 or the floor 14.

A lift sterilizer 40 may be adapted for use with the cabin 12 and an existing HVAC system or as part of a new HVAC system and may typically be mounted above or within the ceiling 18 so that it is maintained in a concealed fashion. However, skilled artisans will appreciate that the lift sterilizer 40 may be maintained on any exterior surface of the cabin, such as the sidewalls, provided that the components of the lift sterilizer do not interfere with the cabin's movement. The lift sterilizer 40 provides for a sterilizer inlet 42 which allows for ambient air maintained within the cabin 12 to be routed through a conduit 44, which may be divided into sub-sections between interconnecting components, and wherein the conduit 44 extends into a sterilizer outlet 46 so that air directed through the sterilizer may be reintroduced into the interior of the cabin 12.

As seen in FIGS. 1 and 2, a sterilizer control system is designated generally by the numeral 50 and serves to connect the components of the lift sterilizer 40 to one another and to the appropriate power mechanisms.

A fresh air blower 52 may be positioned near the blower vent 26 and is maintained within the control system 50. The fresh air blower is typically integrated into the ceiling of the lift cabin 12 to supply outdoor air (from the lift shaft or other external ambient location) to the cabin. In one embodiment, the blower is set to provide at least a constant ten air changes per hour (ACH) inside the cabin as a minimum operating state when ozone level is equal to or below a predetermined threshold level in the cabin as determined by the IAQ sensor, as will be discussed. In another embodiment, the blower is set to provide 15-20 ACH as a maximum operating state when ozone level exceeds the predetermined threshold level in the cabin. Other ACH as the minimum operating state and maximum operating state may be set as desired. 10 ACH is the standard under statutory fresh air requirements. The blower 52 is controlled by a power control module (shown in FIG. 2 as PC) which sets its minimum and maximum status based on a signal from the IAQ sensor as discussed below. The sensor 58 is connected to the fresh air blower 52 by either a wired or wireless connection. In particular, the sensor 58 is connected to the blower's PC so as to place the blower in either a minimum or maximum condition.

The IAQ sensor 58 is maintained within the conduit 44 and, in particular, in close proximity to the sterilizer inlet 42. Skilled artisans will appreciate that the control system 50 along with the sensor 58 and connected components provide the necessary hardware, software, and memory needed to measure selected parameters and enable operation of the control system 50. The sensor 58 measures selected parameters such as particulate matter values PM_(2.5), PM₁₀, and/or ozone levels at a minimum. As used herein, PM_(2.5) refers to fine inhalable particles that are generally 2.5 micrometers and smaller, PM₁₀ refers to inhalable particles with diameters that are generally 10 micrometers and smaller. The sensor 58 is programmed to control the operating status of various components of the system in a manner that will be more fully described. In one embodiment, operation of the AC unit is independent of the sensor 58. In another embodiment, the sensor 58 is also programmed to interface with various components of the AC unit.

A UV-C lamp 60 is positioned within the conduit 44 downstream of the IAQ sensor 58. In the present embodiment, the UV-C lamp is secured within the conduit 44 to deactivate biological contaminants (including bacteria, molds and viruses) by degrading their DNA. A UV-C lamp is a potent sterilization component, yet it does not produce ozone or other harmful by-products. Maintenance cost and energy consumption are also low for UV-C lamps. The UV-C lamp also includes a power control module (PC) which is connected to the IAQ sensor 58 by either a wired or wireless connection. This allows the sensor 58 to turn the UV-C lamp on and off. Skilled artisans will appreciate that the UV-C bulbs typically emit light in the band wavelength of 240-280 nm, which is the energy level sufficient to deactivate biological contaminants without generation of ozone. In one embodiment, the wavelength is 253 nm. UV-C lamp is required to be properly shielded, UV-C lamp damages DNA and skin cells causing health issues ranging from sunburn-like symptoms to skin cancer. Therefore, the UV-C lamp of the present invention is located within the conduit to prevent exposure of the light to cabin occupants. As a result, air passing through the conduit and in proximity to the UV-C lamp deactivates airborne pathogens such as bacteria, mold spores, viruses, and the like.

Positioned between the UV-C lamp 60 and the sterilizer outlet 46 is an ionizer 62 which may or may not be associated with an air conditioner (AC) 64. The ionizer 62 typically provides a pair or protruding “needlepoint” electrodes that extend into the airflow path of the conduit 44. In one embodiment, the ionizer is a bipolar ionizer. The ionizer also provides for a power control module, designated as PC in FIG. 2, and which is connected to the IAQ sensor 58 by either a wired or wireless connection. The sensor 58 can turn the ionizer on and off. It will further be appreciated that the IAQ sensor 58 may or may not be connected to the AC 64 by either a wired or wireless connection so as to turn the unit on and off, provide an on/off schedule, control fan speed, control temperature, and allow for turning on of its fan by the IAQ sensor.

The ionizer 62, and in particular the electrodes, create a high voltage difference which splits passing air and water vapor molecules in the air into a range of positive and negative ions, including but are not limited to N₂ ⁺, O⁺, H⁺, etc. and radicals 3O₂ ⁻, and HO⁻. Depending on the type of ionizer, different charged ions may be released. These charged species deactivate airborne pathogens such as viruses, bacteria, fungi and mold spores by degrading their cellular membrane and stopping them from replicating. In the case of viruses such as COVID-19, the protein coating of individual viral particle is degraded to disable their infectious potential and, as a result, generates H₂O and CO₂ as byproducts. The charged species also cluster around other organic or inorganic particulate matter, volatile organic compounds (VOC) and other pollutants in the ambient air, causing them to accumulate mass and harmlessly fall to the ground where they can be removed periodically by regular mechanical cleaning. The charged ions may be dispersed into the enclosed space and react with airborne and fomite-borne contaminants. The lifetime of these ions is shorter in highly contaminated air as they react upon contact with pathogens and other particulates, but in clean air, the ions typically remain airborne and active in the space for over 100 seconds and any unreacted charges ions simply revert back to harmless water vapor.

Ions created through bipolar ionization are typically present in outdoor air and have no major impact on human health. In the present embodiment, the ionizers are tested to standards such as UL867 to ensure that they do not produce harmful levels of ozone which provides a potential risk of unsuccessful ion recombination, which may have a negative impact on lung health. It has been found that the needlepoint ionizers do not produce harmful levels of ozone unlike older technologies such as corona discharge ionization. However, to ensure that trace levels of ozone inside the cabin are maintained at the lowest possible level, the ionizer may be paired with the fresh air blower discussed above.

Referring now to FIG. 3, it can be seen that a sterilizer control process flow is designated generally by the numeral 100. At step 102 the components of the sterilizer 40 are placed in their initial state of operation. Although not shown, the air conditioner 64 operates between set temperatures as it normally would. The blower 52 are set at a minimum operating condition and the ionizer 62 is placed in the OFF condition. The UV-C lamp 60 is placed in the ON condition. Finally, the IAQ sensor 58 is active and monitoring ozone levels of air being drawn in from the cabin 12 and/or the particulate matter levels. Next, at decision matrix 104 the sensor 58 measures the ozone level and determines whether it is less than or equal to 51 parts per billion (ppb) as shown at condition 106 or not at condition 108. Of course, other threshold values of particulate matter and ozone or other indoor air quality parameters may be used. Additionally, the sensor measures the particulate matter level simultaneously with measuring the ozone layers. In particular, if the particulate matter level PM_(2.5) is less than or equal to 15 μg/m³ and the particulate matter PM₁₀ is less than or equal to 50 μg/m³ then the particulate matter levels are considered normal at condition 110. However, if the particulate matter level PM_(2.5) is greater than 15 μg/m³ and/or the particulate matter level PM₁₀ is greater than 50 μg/m³ then the condition 112 is considered high.

Lookup table 120 examines the conditions 106, 108, 110, and 112 and adjusts operations of the ionizer 62, the blower 52, and the UV-C lamp 60 accordingly. Accordingly, if the ozone level is considered normal and the particulate matter levels are considered normal, then at condition 122 the sensor 58 leaves the ionizer in the OFF condition, the blower 52 in the minimum condition, and the UV-C lamp 60 in the ON condition as the initial state of operation. If the particulate matter level is still considered normal, but the ozone level is considered high, then at condition 124 the ionizer 62 remains in the OFF condition, but the blower 52 is turned to the maximum condition and the UV-C lamp 60 is turned OFF. These states of the components are maintained at condition 124 for a predetermined period of time by a timer.

In the lookup table 120, if it is determined that the ozone level is normal at condition 106 but that the particulate level is considered to be high at condition 112, then at condition 126 the ionizer 62 is placed in the ON condition, the blower 52 is placed in the minimum condition, and the UV-C lamp 60 is placed in the ON condition for a predetermined period of time by a timer.

In a similar manner, if it is determined that the ozone level is high at condition 108 and the particulate matter levels are also considered to be high at condition 112, then at condition 128 the sensor 58 turns the ionizer 62 to an ON condition, the blower 52 to the maximum condition, and the UV-C lamp 60 maintains the ON condition for a predetermined period of time.

Skilled artisans will appreciate that the setting of the time in conditions 124, 126, and 128 may be adjusted as needed. Upon completion of the timed conditions 124, 126, or 128 and the non-timed condition set out at condition 122, the process continues to step 130 which returns all of the components to their initial operating state at step 102. The sensor then repeats the step of checking the ozone and particulate matter levels and proceeds according to their respective conditions. Skilled artisans will appreciate that the testing levels can be adjusted as needed, along with the associated times as is deemed appropriate. Skilled artisans will further appreciate that the ozone testing and the particulate matter testing may be operated concurrently or in a predetermined sequence wherein the ozone is tested first and then the particulate matter; or the particulate matter first and then the ozone levels.

Based on the foregoing the advantages of the present invention are readily apparent. The system mitigates transmission of pathological elements by deactivating airborne and fomite-borne pathogenic materials. The system further mitigates impacts on human health by minimizing the level of PM_(2.5), PM₁₀ and ozone within an enclosed space. Further advantages are realized by utilizing a bipolar ionization and UV-C lamp that does not have any adverse impacts on human health, as no dangerous biproducts are emitted by the system. Prior art lift cabin sterilization solutions utilized UV-C lamps inside the cabin controlled by motion sensors, but these have a potential risk of irradiating occupiers if the sensor operates incorrectly such as by not detecting the presence of the occupants. The system does not provide for moving parts, filters, or consumable components. Therefore, it does not require high levels of maintenance to uphold consistent performance. Additionally, all of the components specified in the system are compact and hidden from sight as they are installed within the HVAC system directly. Moreover, the bipolar ionizer and the UV-C lamp consume lower amounts of power and have little impact on the pressure drop within the HVAC system.

Various modifications and alterations that do not depart from the scope and spirit of this invention will become apparent to those skilled in the art. This invention is not to be duly limited to the illustrative embodiments set forth herein. 

What is claimed is:
 1. A sterilization system adapted for use with a selectively enclosed space, comprising: a conduit having an inlet adapted to draw air in from the enclosed space and an outlet adapted to exhaust air into the enclosed space; an ionizer maintained in said conduit and in close proximity to said outlet, said ionizer releasing charged ions to air flowing through said conduit to selectively deactivate pathogens and air pollutants in the enclosed space and said conduit; a UV-C lamp maintained in said conduit, said UV-C lamp selectively deactivate contaminants in air flowing through said conduit; a blower having a blower vent adapted to exhaust ambient air into the enclosed space; and an air quality sensor maintained in said conduit and in close proximity to said inlet, said air quality sensor measuring at least two parameters, wherein said air quality sensor selectively controls operating states of said ionizer, said UV-C lamp, and said blower based on whether threshold levels of said at least two parameters are exceeded or not.
 2. The system according to claim 1, further comprising: an air conditioner coupled to said conduit, wherein said ionizer is maintained within said air conditioner.
 3. The system according to claim 1, wherein said UV-C lamp is maintained in between said air quality sensor and said ionizer.
 4. The system according to claim 1, wherein said air quality sensor detects at least one particulate matter (PM) level and turns said ionizer on for a predetermined period of time when said particulate matter level exceeds a predetermined PM threshold.
 5. The system according to claim 1, wherein said air quality sensor detects an ozone level and turns said blower from a minimum operating state to a maximum operating state for a predetermined period of time when said ozone level exceeds a predetermined ozone threshold.
 6. The system according to claim 1, wherein said air quality sensor detects an ozone level and turns said blower from a minimum operating state to a maximum operating state for a predetermined period of time when said ozone level exceeds a predetermined ozone threshold, and wherein said air quality sensor detects at least one PM level and turns said ionizer on for a predetermined period of time when said at least one PM level exceeds a predetermined particulate matter level threshold.
 7. The system according to claim 1, wherein said air quality sensor detects an ozone level and at least one PM level and turns said UV-C lamp off for a predetermined period of time when said ozone level exceeds a predetermined ozone threshold and all of said at least one PM level is less than or equal to a predetermined particulate matter level threshold.
 8. A method for sterilizing a selectively enclosed space, comprising: installing a sterilization system in an enclosed space having an air conditioner, wherein the enclosed space has a conduit inlet and a conduit outlet associated with said air conditioner, and a blower vent, said sterilization system further comprising an ionizer, a UV-C lamp, and an air quality sensor maintained in said conduit, and a blower positioned near said blower vent; setting operating states of said blower to a minimum operating condition, said ionizer to an off condition and said air quality sensor and said UV-lamp to an on condition as an initial condition; determining by said air quality sensor whether an ozone value exceeds a predetermined ozone threshold and, whether at least one PM value exceeds at least one predetermined PM threshold and, wherein if both said ozone and PM values do not exceed their respective thresholds, said operating states of said ionizer, said blower, and said UV-C lamp remain in said initial condition, wherein if both ozone and at least one PM value exceed their respective thresholds, said operating states of said ionizer is turned on, said blower is turned to a maximum operating condition and said UV-C lamp remains on for a predetermined period of time, wherein if said ozone value exceeds said predetermined ozone threshold and all of said at least one PM value does not exceed said at least one predetermined PM threshold value, said blower is turned to the maximum operating condition, said ionizer remains off, and said UV-C lamp is turned off for a predetermined period of time, and wherein if said ozone value does not exceed said predetermined ozone threshold value and said at least one predetermined PM value exceeds said at least one predetermined PM threshold value, said ionizer is turned on and said blower remains at the minimum operating condition and said UV-C lamp remains on for a predetermined period of time.
 9. The method according to claim 8, further comprising: positioning said sensor near said conduit inlet.
 10. The method according to claim 9, further comprising: positioning said UV-C lamp between said sensor and said ionizer. 